High actuation force of piezoelectric hybrid actuator with multiple piezoelectric pump design

The piezoelectric hybrid actuator is a new electro-hydrostatic actuator with broad prospects for development. Compared with the traditional hydraulic pump, the piezoelectric hybrid actuator is characterized by a simple structure, small size, lightweight, and low power. However, it has a well-known weakness: It produces only a small actuation force and then cannot be used in real applications. Because the maximum force produced by a one-piezoelectric pump design cannot be increased much due to limitations in the power supply and piezoelectric materials, researchers have moved to the use of multiple piezoelectric pumps. In this research, a double-piezoelectric pump-hydraulic cylinder hybrid actuator was designed, manufactured, and tested in order to increase the actuation force. Key design factors such as the connection method and driving method were investigated to realize the double-piezoelectric pump design and achieve a high level of performance. A total of three kinds of double-piezoelectric pump-hydraulic cylinder hybrid actuator designs were selected by a theoretical approach and implemented using two identical piezoelectric pumps. A manual valve system was installed for switching the connection method (series and parallel modes). The driving method, phase, or voltage was controlled by a LabVIEW program. The maximum blocking force of 4615 N was measured at 250 Hz for cross driving, series connection and φ30-mm cylinder. The maximum velocity of 68.3 mm/s was measured at 300 Hz for cross driving, series connection and φ21-mm cylinder. Fluid structural interaction analysis using ANSYS software confirmed the experimental results. The performance of double-piezoelectric pump-hydraulic hybrid actuator meets the minimum requirements for mechanical and aerospace actuator applications.